In a bid to help the spice market of Northeast, a team of IIT-Guwahati led by Professor P Muthukumar have developed an affordable solar dryer that increases the shelf-life of spices.

In an exclusive interaction with EastMojo, Prof Muthukumar said Northeast is called the ‘spice hub of India’. Several high-value agricultural products, such as cardamom and high-quality ginger and chilli, are produced here.

“But currently, the technology used for preserving these spices are simple, like open-sun drying, or sometimes large-scale farmers go for smoke-drying method. Both these technologies are having their inherent demerits, and you cannot preserve the actual quality of the product because of the long drying time,” he said.

Explaining why, the Professor said, “Sometimes because of the long drying time, you can see the formation of fungal growth over the product. And more than 20 to 30 percentage of the product gets spoiled during the drying period. This is a huge financial loss for the farmers. Particularly, if you see the long cardamom, which in the market is available at the rate of about Rs 10,000. If farmers lose 1 kg of cardamom, the loss will be about Rs 10,000.”

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To solve this issue of produce getting spoiled, the IIT-G team has worked on a low-cost solar dryer, mainly for farmers from the Northeast.

Prof Muthukumar said, “The dryer we developed can dry nearly about 30-40 kg of any product at a time. Compared to the open sun drying method, if you use our dryer, you can dry your product within a maximum of two days. You can reduce the drying time by almost 50%. And at the same time, the colour will be more or less like the original colour. So you can preserve the colour as well. Also, we have done all the quality checks, like antioxidant quality, protein, and all other properties. Whatever product has been tried on the solar dryer by IIT Guwahati, the original quality was preserved.”

On the expenditure and materials required to make the machine, the professor said, “This is an indigenously developed technology and can be manufactured locally. Maybe we need to have some plywood then some glass, but these are all locally available. The cost will be approximately Rs 20,000 to 25,000.”

He added that the solar dryer can be used for drying any agricultural product.

The Professor is hopeful that their device will elevate the income of farmers. They also plan on fabricating such dryers and deploying them in various parts of the Northeast and provide training to farmers so that they can use the device efficiently.

How it works:

The IIT Guwahati Solar dryers use solar energy or radiation to dry food substances, especially agricultural products, to preserve them. The solar dryer has an absorbing surface that can absorb solar radiation and gain heat from it. The thermal energy is then used to remove the moisture content from the products, hence, drying up the product in the process.

There are three general types of solar dryers: Direct, Indirect and Mixed mode.

In the direct solar drying mode, the substance is exposed to be dehydrated in direct sunlight. Here, the product directly gains heat from sunlight and to be dried. In this case, there can be chances for contamination of the product by dust from wind, birds, insects, or animals.

In the case of the indirect solar drying method, the air is heated separately by using a solar air heater and the hot dry air with a low percentage of relative humidity is passed to the dryer chamber where the product is placed. Here, direct sunlight is not allowed on the product as the direct sun can chemically alter the contents of the product, making them less appetizing.

In the mixed mode of drying, solar radiation is allowed to enter the drying chamber to heat the products inside and hot air is also supplied to the drying chamber from a separately connected solar air heater. In this case, the dryer receives heat from both solar radiation and hot air, due to which the drying rate is much faster.

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